The problem of trying to keep out sound or noise is an old one. For this reason acoustical seals have been used in a variety of circumstances when it is desired that the noise level in one enclosure be significantly lower than the noise level in a neighboring enclosure. Certain materials have been found to be better at keeping out sounds than others, and it is well known that the more mass of a particular material placed between one enclosure and another, the more the sound will be kept out. Normally, there must be access to the enclosure having the low sound level, and it is for this reason that there must be seams or cracks which further need to be acoustically sealed. This too is a well known problem as evidenced by the prior art. For example, see U.S. Pat. Nos. 1,365,425; 3,506,981; and 3,593,341. While much work has been done to solve this problem, the problem has heretofore never been solved completely and satisfactorily.
The general type of device shown in the above noted patents is in the form of an enclosure known as an ear muff. It is well known that the hearing of people working in a noisy environment can easily be damaged, and it is common to wear ear muffs to reduce the sound level to which the ear itself is subject. An ear muff, generally, is a dish of solid material shaped so as to cover completely at least one ear and to press at its open edge on the face around the ear. The muff can relatively easily be made such that the reduction of noise through the material of the muff itself is satisfactory to keep out a very high proportion of any noise, but it is difficult to prevent noise from leaking between the edge of the muff and the face. Clearly the edge of the muff cannot be made to fit exactly to each individual face, and it has been the practice to line the edge of the muff with a spongy material such as natural rubber, or with an expanded soft plastic. If such an ear muff is pressed against the face with sufficient force, the reduction in the noise is relatively satisfactory, but the pressure on the face is normally too high for comfort. This discomfort is intensified if the wearer of the ear muffs wears glasses or spectacles. Alternatively, the edge of the ear muff has been lined with an oil-filled flexible material, but this too, because of the pressure required, can be uncomfortable when pressed against the face, it is quite expensive and additionally it sometimes leaks.